The overall objective of the research supported by this grant is to characterize the neurochemical and neuroendocrinological effects of the narcotics, particularly with respect to the role these changes may play in the acute actions of these compounds and the cellular adaptations occurring during their chronic administration (i.e., tolerance and physical dependence). The studies fall into two general classes: First, to examine the effects of the narcotics on catecholamine-containing systems in brain and, conversely, to attempt to modulate the actions of the narcotics by selective alterations in the activity of these pathways; and, secondly, to examine and characterize the effects of the narcotics on reproductive endocrinology in the male.